TALON Cobalt Resin Beats Ni-NTA Resin

The cobalt ions in TALON are more selective for histidine tags than nickel ions are. This means that using Ni-NTA resins often results in copurification of contaminants. Another advantage of TALON resin is that you can elute your his-tagged protein at a mild pH or lower imidazole concentration.

Figure 1. 6xHN-AcGFP1 was purified from Sf21 cells using TALON (left) or Ni-NTA (right). The chromatogram for each column is shown. The absorbance at 475 nm indicates the amount of target protein (AcGFP1) present in each fraction.

Figure 2. 6xHis-tagged protein (prepro-alpha-factor) was loaded onto TALON and Ni-NTA columns, eluted by stepwise pH, and analyzed by SDS-PAGE. The protein was eluted from TALON resin at pH = 6.3 and from Ni-NTA resin at pH = 4.5.

TALON Resin is Compatible with Beta-Mercaptoethanol (BME)

Reduced sulfhydryl (-SH) groups are important to the biological activity and structure of some intracellular proteins, and BME is often used to preserve these reduced -SH groups. TALON resin provides higher yields of his-tagged proteins that contain reduced -SH groups in the presence of BME compared to Ni-NTA resin.

Figure 5. N-terminal 6xHis-tagged DHFR was expressed and purified under native conditions. Protein concentrations
were determined by Bradford assay. Yields are expressed as a percentage of total protein in the cell lysate.

TALON Resin: Cobalt is the Key to His-Tagged Protein Purification

TALON resin is based on the cobalt ion, which is highly selective for his-tagged proteins (1-3). This makes TALON resin a better choice than Ni-NTA resin:

TALON resin has better specificity for his-tagged proteins than nickel-NTA. In TALON, only proteins containing adjacent histidines or specially positioned, neighboring histidines are able to bind. By comparison, the spatial requirements for Ni-NTA resin are less strict—these resins have a much higher affinity for randomly positioned (i.e., non-his tag) histidines. As a result, TALON resin binds more specifically to polyhistidine-tagged proteins and provides higher purity.

TALON resin has low metal ion leakage. Cobalt resin has a very uniform three-dimensional structure in which cobalt is bound very tightly. Nickel-based resins are less homogeneous in structure because nickel ions can form two different coordination complexes, one of has a planar (flat) structure that does not bind the nickel ions tightly. Thus, nickel ions can leach from the resin.

Why is metal ion leakage bad?

Metal leakage reduces the number of reactive sites available for protein binding, and therefore reduces the yield of purified protein.

Free metal ions have a detrimental effect on protein activity.

Metal ions can precipitate proteins by forming salt bridges, can be toxic to cells and tissues, and can damage purified protein because of its nucleophilic properties.

We Also Recommend

ProteoGuard Protease Inhibitor Cocktail
Use this protease inhibitor cocktail to suppress proteolysis in all your cell lysates. We recommend using ProteoGuard with all our protein purification products.